(1) Technical Field
This invention relates to pipe couplings for connecting two pipe sections to one another and more particularly to a locking device that will hold the pipe in axial alignment with the coupling and prevent relative rotation between the pipe and the coupling.
(2) Description of the Prior Art
A pipe coupling with a cam tightening device is shown in U.S. Pat. No. 2,935,342 and takes the form of a split clamping ring and a pair of sleeves engagable therewith when the ends of the split ring are moved toward one another.
U.S. Pat. No. 3,148,902 discloses a coupling between spigot and bell ends of pipe sections and positions cam blocks in the area between the ends and provides means for moving the cam blocks relative to one another so as to wedge the pipe ends in connected position.
U.S. Pat. No. 3,158,388 utilizes spaced rings having annular cam surfaces wedging against a third ring and bolts for moving the spaced rings in a wedging action.
U.S. Pat. No. 3,669,475 shows a compression coupling in which bolts move inwardly of the ends of the coupling and urge annular wedges into opposed configurations of the coupling.
The present invention differs from each of these prior art disclosures in that the coupling, such as for example that shown in U.S. Pat. No. 4,138,146, is provided with a longitudinally extending offset boss arranged to cage and thereby position an elongated rotatable cam member against the side of a pipe engaged in the coupling. The rotatable cam member is thereby positioned transversely of the pipe and when moved into engagement between the pipe and the boss is rotated to bring its caming surface into position wedging the pipe so as to prevent the same from rotating relative to the coupling or the coupling from rotating relative to the pipe and more importantly to prevent the pipe from sagging as by moving out of its longitudinal axial alignment with the coupling.